Cannot patition Kali USB as per instructions

Hi,
I successfully installed Kali to USB 8GB flash drive. However, I want to use the persistent option and am Trying to create a new partition using the instructions here: https://www.kali.org/docs/usb/kali-l...b-persistence/ but when I run the command:
read start _ < <(du -bcm kali-linux-2020.1-live-amd64.iso | tail -1); echo $start
parted /dev/sdb mkpart primary $start $end

it says "cannot access kali-linux-2020.1-live-amd64.iso: no such file or directory

I am running Linux Mint live from a CD and am running the command as root using sudo su.

Can someone please advise where I am going wrong or how to fix this so I can use the persistence option?
Thanking you

I know this is old, but I had the same error. add the path to the start of the iso name. Should look something like: \home\[username]\Downloads\kali-linux....